1 Shell patterns as dynamic systems.- 2 Pattern formation.- 3 Oscillations and travelling waves.- 4 Superposition of stable and periodic patterns.- 5 Meshwork of oblique lines and staggered dots.- 6 Branch initiation by global control.- 7 The big problem: two or more time-dependent patterns.- 8 Triangles.- 9 Parallel lines with tongues.- 10 Shell models in three dimensions.- 11 The computer program.- 12 Pattern formation in the development of higher organisms.- References.